David Wallinga, with the Institute for Agriculture and Trade Policy, is among those who argue that overusing antibiotics contributes to antibiotic resistance that could be passed on to humans.

John Paterson, an extension beef specialist at Montana State University, said there is no solid evidence that beef raised without antibiotics is healthier.

"But, as meat producers, if the consumer wants the product, we're going to produce that product for them," he said.

Producers who market their beef as raised without antibiotics must document their procedures for the Agriculture Department's Food Safety and Inspection Service, a spokeswoman said. The federal agency must approve labeling of products making special claims, such as "raided without antibiotics."

T.G.I. Friday's now serves Meyer Natural Angus burgers in its restaurants, a decision bolstered by the meat's taste and performance in consumer surveys, said Tom Koenigsberg, vice president of domestic marketing for the chain.

"The premiums we're offering can make it so, in the bad years, (a cattle rancher) breaks even and in the rest of the years, he makes double what he would have. That's pretty significant," said Leachman.

Killman said the market represents an opportunity for ranchers.

"We, as cattlemen, are going to have to target our cattle to some specific market," he said. "We can't just go out and raise cattle and then hope that somebody buys them."

Billings, Montana Ranchers hungry for meatier returns on their cattle are weighing their production options and more of them are doing away with antibiotics.

"Demand has been more than we ever anticipated," said Ray Killian, president of Meyer Natural Angus.

The company plans this year to slaughter about 35,000 cattle raised according to its strict protocol, which focuses on animal health and avoids antibiotics and growth hormones. The Missoula, Montana, company's planned production is nearly double what they recorded last year.

From natural food stores to supermarkets and mainstream restaurants, beef raised without antibiotics has found a receptive audience, including health conscious meat eaters and those who simply want a better idea of where their cuts originated.

With an eye toward that market, some beef producers have also cut out growth hormones, which are sometimes used to fatten animals before slaughter.

Killian said raising cattle without antibiotics is more than just an effort to capitalize on a niche market.

"What it does is force us to have a 'well-animal program' to keep the animals healthy so they don't have to be treated, and I think that's a positive contributor to the taste and the quality of the product," Killian said.

At Meyer Natural Angus and Montana Range Meat Co., a Billings-based operation, cattle requiring antibiotics for health reasons are removed from the herd, treated and later sold at traditional markets.

Potential health benefits from beef raised without antibiotics are still being debated.